A redundant array of inexpensive disks level six (RAID-6) sub-system may utilize two redundancy strips, parity and Q, in a stripe to aid in reconstructing a RAID volume in case of a single or double disk drive failure. A RAID controller operating to update a data strip in the stripe may be required to update parity and Q associated with the stripe to ensure that the data is doubly protected. If an unexpected reset (e.g., a reset caused by a power failure) intervenes while the write is in progress, it may be difficult to determine which updates have been completed. Thus parity and Q associated with the affected stripe may both require re-calculation at the next re-boot following the power failure. Data in the strip targeted by the write in progress may be indeterminate, since the write to the targeted strip may have been interrupted by the power failure. However, data on parallel strips in the stripe may be unaffected by the power failure. If both the power and a disk drive fail during write operations, upon re-boot both parity and Q may be indeterminate. In the latter case, the entire volume may be failed since it may not be possible to rebuild the stripe correctly.